In the past year, we have made significant progress towards realizing the goals of this project. As of August, we have completed a set of slice recording experiments comparing the basic electrophysiological properties of astrocytes in midbrain regions with those of astrocytes in the cortex and hippocampus. These experiments also allow us to determine the extent to which astrocytes and oligodendrocytes are coupled within each brain region by visualizing the diffusion of small molecule tracers (e.g. biocytin) loaded into a single astrocyte. Since astrocytes exhibit complex patterns of calcium signaling, weve also profiled the calcium activity of midbrain and hippocampal astrocytes in response to a number of agonists. In addition to these functional assays, we have worked out a successful protocol for acutely isolating astrocytes from adult brain tissue via a combination of microdissection and fluorescence activated cell sorting (FACS). As of right now, astrocyte RNA transcripts from several brain regions have been sequenced and analysis of these data is ongoing. Finally, we are working to secure mouse lines that will enable us to probe the function of an enzyme involved in glutamate homeostasis that is selectively abundant within midbrain oligodendrocytes.